Determination of antimicrobial resistance pattern of staphylococcus aureus isolated from clinical specimens

ABSTRACT

Staphylococcus aureus is an important cause of nosocomial and community-acquired infections. The emergence of antibiotic resistance, especially in methicillin-resistant SA [MRSA] strains, has caused difficulties in treatment of such infections. The determination of antibiotic resistance patterns, particularly domestic patterns of Iran, is essential for appropriate treatment of MRSA infections and proper infection control measures in our country. The antibiotic resistance of 338 SA isolates from various clinical specimens was determined by disk agar diffusion [DAD], minimum inhibitory concentration [MIC] and polymerase chain reaction [PCR] methods. Using the DAD method, 47% [160/338] of the SA isolates were resistant to oxacillin, and only 6% [20/338] were resistant to vancomycin. By PCR, 48% [162/338] of the isolates had the mecA gene. The MIC of oxacillin in 93% of isolates was higher than 256 micro g/mL. The MRSA isolates, showed a high resistant to gentamicin [40.5%], erythromycin [40%], and ciprofloxacin [38%]. However, only a few of the SA isolates showed a high resistance to vancomycin [5%] or erythromycin [3.5%]. The results of this study can provide guidance for physicians toward a more appropriate treatment of SA infections in Iran, thereby preventing the emergence of further antibiotic resistance among SA. Our results also revealed the need for further investigations using a higher number of specimens representing a wider variety of locations to determine the antibiotic resistance patterns in our state more precisely